Re: [PATCH v1 5/5] KVM: s390: vsie: gmap_table_walk() simplifications

Janosch Frank
2020-04-03T13:03:25Z

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On 4/2/20 8:48 PM, David Hildenbrand wrote:
> Let's use asce_type where applicable. Also, simplify our sanity check for
> valid table levels and convert it into a WARN_ON_ONCE(). Check if we even
> have a valid gmap shadow as the very first step.
>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
> arch/s390/mm/gmap.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
> index fd32ab566f57..3c801dae7988 100644
> --- a/arch/s390/mm/gmap.c
> +++ b/arch/s390/mm/gmap.c
> @@ -790,17 +790,18 @@ static inline unsigned long *gmap_table_walk(struct gmap *gmap,
> const int asce_type = gmap->asce & _ASCE_TYPE_MASK;
> unsigned long *table;
>
> - if ((gmap->asce & _ASCE_TYPE_MASK) + 4 < (level * 4))
> - return NULL;
> if (gmap_is_shadow(gmap) && gmap->removed)
> return NULL;
>
> + if (WARN_ON_ONCE(level > (asce_type >> 2) + 1))
> + return NULL;
> +
> if (WARN_ON_ONCE(asce_type != _ASCE_TYPE_REGION1) &&
> gaddr & (-1UL << (31 + (asce_type >> 2) * 11)))
> return NULL;
>
> table = gmap->table;

We could also initialize this variable at the top, no?

> - switch (gmap->asce & _ASCE_TYPE_MASK) {
> + switch (asce_type) {
> case _ASCE_TYPE_REGION1:
> table += (gaddr & _REGION1_INDEX) >> _REGION1_SHIFT;
> if (level == 4)
>

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